Marine & Boat Machined Parts — Corrosion Resistant

What this industry requires

Marine and offshore hardware lives in salt water, spray and constant moisture, so the first question a buyer asks is material, not price. A deck cleat, through-hull fitting or shaft coupling that corrodes early can mean a haul-out, a failed seal or a part that cannot be removed without cutting it off. That is why marine drawings usually name the grade — 316L or a bronze-family copper alloy — and why we machine to that grade rather than substituting.

We machine marine parts to a general tolerance of ISO 2768-m and hold ±0.01 mm on the precision features the drawing calls out, such as bearing fits, sealing faces, threads and concentric bores. Threads in particular need to stay clean and within class so fittings seal and fasteners torque properly in service. Quotes come back within 24 hours with DFM feedback, and we flag the features that drive cost — deep threads, thin walls and long internal bores — so the quote reflects the drawing rather than a guess.

Parts we machine for this industry

The parts we machine for this industry split into propulsion, deck and plumbing work. Shafting and couplings carry load and need concentric features machined in one setup so the shaft line runs true. Deck hardware — cleats, bollards, hinges, brackets and mounts — is machined for strength and a clean, snag-free profile. Through-hull fittings and valve bodies need accurate threads and flat sealing faces that hold against the hull. Dock and mooring hardware such as cleats, plates and brackets is machined for long-term exposure to seawater and repeated loading. Where a part carries both turned and milled features, such as a coupling with a keyway or a cleat with a profiled base, we keep the work in one setup.

Round parts route through CNC turning and prismatic parts through CNC milling, with composite work kept in one setup. For related part families see custom shafts, flanges and couplings, custom brackets and the industries we serve.

Materials and standards commonly used

Stainless 316 and 316L are the workhorses for salt water because their molybdenum content resists the chloride pitting that attacks ordinary grades. Stainless 304 and 304L are fine for fresh water and interior work, but in stagnant salt water they can pit and crevice-corrode, especially on fasteners and sheltered hardware — which is why 304 is often the wrong choice once a part sits wet and out of the flow. We machine 301, 303, 304, 304L, 316, 316L, 410, 416 and 17-4PH, we machine the grade the drawing names, and the materials page sets out what each one suits.

For hardware where the drawing calls for a copper alloy, the choice is usually between a bronze-family alloy and brass. We machine brass and copper from our confirmed list, and we review any bronze-family grade named on the drawing so the quote reflects the exact material. Galvanic corrosion is handled at a general level: we follow the material pairing the drawing states so dissimilar metals are not placed in direct seawater contact without the intended isolation, and we keep threads and contact faces clean. Surface treatment — passivation, electropolishing and polishing — runs through our vetted partner network under one quality process. See materials and surface finishes for the confirmed options. The exact grade is named on the material certificate (MTR) that ships with the order, so the alloy reaching the boat is the one the drawing calls for.

What ships with your order

Every order ships with a material certificate (MTR) for the raw material and pre-shipment photos of the finished parts, so the grade can be confirmed before the parts go on board. Ordering starts from 50 pieces per style and material, with samples from one piece in 5–10 days and production in 25–35 days after sample approval. Monthly capacity is over 100,000 parts with a milling envelope of 800 × 500 mm. Samples can be machined from one piece so you can trial a fitting or fastener on board before committing to a batch. Send your drawing through the request a quote form or WhatsApp and we return DFM feedback within 24 hours.

Marine parts are a materials problem before they are a machining problem: a 316 or bronze part that machines well and survives salt water beats a tighter part in the wrong grade. The stainless route is covered under stainless steel parts, and the fasteners that usually accompany a marine assembly under custom screws.